Digital Twin Framework for Modeling the
Aqueous Degradation of Allicin and Its Nanocomplexes: Integrating DFT
Thermodynamics, Molecular Dynamics Surrogate, and Experimental Validation
Jefferson
Lorençoni de Morais1,2*, Heliel Gabriel Borges de Sena3, Larissa Neres Barbosa3, Lanna Araújo Gomes3.
1* Polytechnic School of the Alves Faria University Center —
UNIALFA, Goiânia, Brazil
2* American University of Global Technology - AGTU,
Orlando, USA.
3 Institute of Pharmaceutical and Exact Sciences — University
Center of Goiás — UNIGOIÁS, Goiânia, Brazil.
*Correspondence: Jefferson.morais@unialfa.com.br;
DOI: https://doi.org/10.71431/IJRPAS.2026.5406
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Article
Information
|
|
Abstract
|
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Research Article
Received: 24/04/2026
Accepted: 27/04/2026
Published:30/04/2026
Keywords
Allicin, Digital Twin;
Nanocages;
Al₁₂N₁₂;
Molecular Dynamics
Surrogate.
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Allicin (diallyl thiosulfinate), the
principal bioactive compound of Allium sativum (garlic), exhibits
well-documented anticancer, anti-inflammatory, antiviral, and antibacterial
activities [1,2].
However, its rapid degradation in aqueous environments represents a critical
pharmacological limitation. This study presents the first Digital Twin (DT)
framework for modeling allicin aqueous stability, integrating three
computational layers: (1) a thermodynamic ODE kinetic engine parametrized by
DFT data (Ead, ΔH, ΔG) from Al₁₂N₁₂, B₁₂N₁₂, and C₂₄ nanocomplexes [1]; (2) a Gaussian Process
surrogate emulating GROMACS molecular dynamics outputs — RMSD, radius of
gyration (Rg), solvent-accessible surface area (SASA), and B-factors; and (3)
an experimental validation layer calibrated against published stability,
UV-Vis, IR, and molecular docking data. The Allicin/Al₁₂N₁₂ complex achieved
a Nanocage Protection Factor (NPF) of 5,498,905× at 37 °C, pH 7.4, extending
the half-life from 3.6 days (free allicin) to beyond 9,999 days. The MD
surrogate predicted equilibrium RMSD of 0.485 Å and SASA of 6.96 nm² for the
Al₁₂N₁₂ complex, consistent with strong encapsulation. Stability validation
yielded R² = 0.9997 and MAPE = 10.3% against literature data [27,28]. IR frequencies were
reproduced within 1.18% [1,7].
This work establishes Digital Twin methodology as a novel paradigm for
computational drug delivery optimization of natural bioactive compounds.
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INTRODUCTION
1.1
Garlic (Allium sativum L.): Botanical and Chemical Overview
Garlic (Allium sativum
L.) has been used as food and medicine for over 5,000 years across Egyptian,
Greek, Roman, Chinese, and Indian traditions [2]. Taxonomically, it
belongs to the family Alliaceae and is divided into two subspecies: A. sativum var.
sativum (softneck garlic, up to 24 cloves) and A. sativum var.
ophioscorodon (hardneck garlic, 6–11 cloves) [3]. Its remarkable
pharmacological versatility derives from sulfur compounds comprising 1–3% of
dry weight [4]. The biosynthetic
pathway begins with alliin (S-allyl-L-cysteine sulfoxide) in intact cloves;
upon mechanical disruption, alliinase (EC 4.4.1.4) converts alliin to allicin,
pyruvate, and ammonia [4,5].
Beyond allicin, garlic
contains diallyl disulfide (DADS), diallyl trisulfide (DATS), ajoenes,
vinyldithiins, S-allylcysteine (SAC), and S-allylmercaptocysteine (SAMC) [2].
S-1-propenyl-L-cysteine (S1PC), a stereoisomer of SAC found predominantly in
aged garlic extract (AGE), exhibits immunomodulatory and antihypertensive
activities with oral bioavailability of 88–100% in animal models [6]. Black
garlic — a fermented form produced under controlled temperature and humidity —
concentrates polyphenols and Amadori compounds, demonstrating superior
anti-inflammatory and anticancer activities with reduced side effects compared
to raw garlic [3].
1.2
Allicin: Structure, Properties, and Biological Activity
Allicin (C₆H₁₀OS₂; CAS
539-86-6) was first isolated by Cavallito and Bailey in 1944 [5] and confirmed by total
synthesis in 1947 through mild oxidation of diallyl disulfide. Its
thiosulfinate group — flanked by two allyl chains — confers high reactivity
with thiol-containing biomolecules, characterized by S=O (ν = 1065–1070 cm⁻¹)
and S-S (ν ≈ 470 cm⁻¹) stretching modes [7,1]. The principal
antimicrobial mechanism involves inhibition of thiol-dependent enzymes
including alcohol dehydrogenase, thioredoxin reductase, and RNA polymerase [4], conferring
broad-spectrum antibacterial activity against Gram-negative and Gram-positive
bacteria, antifungal activity against Candida albicans, and antiparasitic
activity against Entamoeba histolytica and Giardia lamblia [4]. From an anticancer
perspective, allicin induces apoptosis in multiple cancer cell lines —
including HONE-1 and HNE1 nasopharyngeal carcinoma via ferroptosis [8] — and suppresses
oncogene expression while upregulating tumor suppressors [9]. Anti-inflammatory
effects involve NF-κB pathway modulation, TNF-α reduction, and attenuation of
oxidative stress [10]. Antiviral potential
against SARS-CoV-2 main protease (Mpro) has been reported computationally [1].
1.3
Limitation: Aqueous Instability of Allicin
Despite its broad pharmacological profile,
allicin's principal limitation is chemical instability in aqueous media. It
undergoes degradation through thiosulfinate hydrolysis, disproportionation, and
thermal decomposition, yielding DADS, DAS, ajoenes, and vinyldithiins [11].
Under physiological conditions (37 °C, pH 7.4), t½ ≈ 3.5–4 days; at 50 °C, t½ ≈
1.1 days [28]. This instability severely constrains bioavailability and
therapeutic application. Nanocarrier strategies using C₂₄, B₁₂N₁₂, and Al₁₂N₁₂
nanocages have been computationally explored [1]. The Al₁₂N₁₂ complex
demonstrates Ead = −40.28 kcal/mol and ΔG = −27.33 kcal/mol in water phase,
indicating spontaneous, thermodynamically favorable complex formation [1].
1.4
Digital Twins in Materials and Pharmaceutical Sciences
The Digital Twin (DT)
concept — a dynamic computational replica continuously updated with real-world
data — originated in aerospace engineering. In materials science, Xu et al. [12] developed a
physics-informed DT integrating viscoplastic self-consistent (VPSC) models for
real-time creep prediction in Mo-Re alloys, capturing evolving microstructural
mechanisms that purely empirical models cannot resolve. Vairagade [13] applied a five-layer
multiscale DT to fly ash-based concrete, reducing RMS force prediction errors
from 0.31 to 0.09 eV/Å through DFT-derived Gaussian Approximation Potentials.
Haverkamp et al. [14] demonstrated DT
potential for road infrastructure monitoring and sustainable lifecycle
management. In pharmaceutical science, however, DT methodology remains largely
unexplored for natural bioactive compounds. This work addresses that gap.
1.5
Objectives
This study aims to: (i)
develop a three-layer Digital Twin for allicin aqueous degradation parametrized
by DFT thermodynamic data [1]; (ii) implement a Gaussian Process (GP) surrogate
emulating key GROMACS observables (RMSD, Rg, SASA, B-factor); (iii) validate
the DT against published experimental data; and (iv) quantify nanocage
protection factors under physiological conditions.
2.
PROBLEM STATEMENT
The central challenge
is formally stated as: the half-life of free allicin in aqueous medium at
physiological conditions is insufficient for therapeutic application, and no
existing computational tool provides a dynamic, multi-scale, experimentally
calibrated prediction of allicin stability across formulation conditions.
Existing DFT studies [1] yield static thermodynamic parameters without temporal
dynamics. GROMACS MD simulations are resource-intensive and cannot assimilate
experimental data in real time. No validated model connects DFT ΔG values to
macroscopic half-life under variable T and pH with literature
cross-validation.The guiding research questions are: (Q1) Can DFT adsorption
free energies parametrize a kinetic model that accurately predicts allicin
half-life? (Q2) Can a Gaussian Process surrogate faithfully emulate GROMACS
structural observables? (Q3) Does the Digital Twin reproduce experimental
stability, spectroscopic, and docking data with acceptable quantitative
accuracy?
MATERIALS AND METHODS
3.1
Digital Twin Architecture
The Allicin Digital Twin v2.0 consists of
three tightly coupled layers implemented in Python 3.12 (NumPy, SciPy,
scikit-learn). Layer 1 provides physics-based kinetics; Layer 2 emulates MD
structural observables; Layer 3 validates against experimental data. A
Nelder-Mead data assimilation module calibrates the activation energy Ea
against any time-resolved experimental observations, making the DT adaptive.
3.2
Layer 1 — Thermodynamic ODE Kinetic Engine
Allicin degradation in aqueous medium was
modeled as a pseudo-first-order process using the Arrhenius equation:
k(T) = A · exp (−Ea / RT) ... (1)
The pre-exponential
factor A was anchored to the experimental reference t½ = 16 days at 23 °C, pH
7.0 [27], giving Kref = 5.02 ×
10⁻⁷ s⁻¹. A pH correction factor was applied:
f(pH) = 1 + 3· [1 − exp (−(pH − 7.0) ² /
12.5)] ... (2)
The Nanocage Protection
Factor (NPF) derived from DFT Gibbs free energy [1]:
NPF = exp (α · |ΔG_complex| · 4184 / RT),
α = 0.35 ... (3)
where α = 0.35 is the
coupling fraction representing the proportion of complex formation free energy
transferred to the degradation activation barrier. This value was determined by
calibration against the six experimental half-life data points (Table 4):
values of α between 0.30 and 0.40 were evaluated via grid search, with α = 0.35
minimizing MAPE across all conditions. Physically, α < 1 reflects the
thermodynamic expectation that only a fraction of the complexation energy is channeled
into kinetic stabilization — the remainder partitions into conformational
entropy and non-covalent reorganization terms not directly coupled to the
degradation transition state. This is consistent with the Marcus-type treatment
of activation barriers in host-guest systems [25]. The degradation rate
for each complex is k_complex = k_free / NPF. Five coupled ODEs tracked free
allicin, three complexed forms, and degradation products, solved by LSODA (rtol
= 10⁻⁹, atol = 10⁻¹¹).
3.3
Layer 2 — Gaussian Process MD Surrogate
The surrogate emulates four GROMACS
observables: RMSD (Å), Rg (Å), SASA (nm²), and B-factor (Ų). Physics-based
analytical models were derived from statistical mechanics principles to
generate physically consistent training data for the GP emulator. These
analytical expressions do not constitute actual GROMACS trajectories; rather,
they provide a theoretically grounded synthetic dataset from which the GP
learns input-output relationships. Their derivations are as follows:
• RMSD equilibrium:
Derived from the equipartition theorem applied to a harmonic binding potential.
For a molecule in a binding well of stiffness k_spring ∝ |Ead|, thermal
fluctuations give ⟨x²⟩ = kT/k_spring, so RMSD_eq ∝ √(kT/|Ead|) from equipartition applied to harmonic binding; the relaxation
timescale follows an Arrhenius-type relation, τ_RMSD ∝ exp(α|Ead|/RT).
• Rg: The radius of
gyration measures the mass-weighted spatial distribution of atoms. Upon
encapsulation, the complex becomes more compact. Starting from free-allicin Rg₀
≈ 5.8 Å, the compaction is modeled as ΔRg ∝ ln(1+|Ead|), a logarithmic form consistent with diminishing compaction
returns at high binding energies, as observed in MD studies of nanoconfined
molecules [25,26].
• SASA: The
solvent-accessible surface area was modeled as an exponential decay with
binding energy: SASA_eq = 14.2·exp(−0.018·|Ead|) nm². The functional form
reflects the physical expectation that deeper encapsulation progressively
excludes solvent molecules, approaching an asymptotic minimum surface at high
|Ead|. The parameters (14.2 nm² reference and decay constant 0.018 mol/kcal)
were derived by fitting to SASA values reported in analogous nanocage-drug
encapsulation studies [25,26], reflecting solvent
exclusion upon encapsulation.
• B-factor: Atomic
displacement parameters were computed from the Debye-Waller relation B = 8π²⟨u²⟩/3, ⟨u²⟩ ∝ kT/k_spring, k_spring ∝ |Ead|.
It is important to note
that no actual GROMACS molecular dynamics simulations were performed in this
work. The GP surrogate was trained entirely on synthetic data generated by
evaluating the physics-based analytical expressions described above across a structured
parameter grid — a methodology analogous to physics-informed surrogate modeling
[12,13]. This approach is computationally efficient and
transparent, enabling uncertainty quantification via GP posterior variance,
while the analytical functions themselves encode the relevant physical
constraints. Training set: N = 400 points on grid (T ∈ [278, 325] K, Ead ∈ [−50, −2] kcal/mol, t ∈ [0.1, 200] ns) with Gaussian noise (σ ≈ 0.04) added to simulate
measurement uncertainty. Four independent GP Regressors (Matérn kernel, ν =
2.5, n_restarts = 3) were trained with StandardScaler normalization, providing
mean trajectory and ±1σ uncertainty bands. For full reproducibility, all random
seeds were fixed (numpy. random.seed(42)), training grids were generated deterministically,
and the complete Python 3.12 implementation (NumPy 1.26, SciPy 1.13,
scikit-learn 1.4) is available from the corresponding author upon request.
3.4
Layer 3 — Experimental Validation
Stability validation: six data points for
free allicin t½ at T = 4–50 °C and pH = 5–9 from Miron et al. [27], Lawson & Wang [28], and Block [7]. UV-Vis validation:
free allicin λmax = 242 nm, ε = 26,500 L/mol·cm [29]. IR validation: S=O,
S-S, O-B, and O-Al modes from Block [7] and Mozafari et al. [1]. Docking validation:
EDc and Ki for allicin and nanocomplexes against HER2 (3RCD), TNF-α (2AZ5),
COVID-19 Mpro (6LU7), and S. aureus (3VSL) from Mozafari et al. [1]. Metrics: RMSE, MAPE,
Pearson R². Data assimilation yielded calibrated Ea = 17.75 kcal/mol (prior:
19.1 kcal/mol).
RESULT
AND DISCUSSION
4.1 DFT Parametrization
The thermodynamic input data (Table 1) derive from the
PBE1PBE-D3/6–31+G** calculations of Mozafari et al. [1] with GD3BJ dispersion correction in Gaussian
09. All Ead values are negative, confirming spontaneous adsorption. The Al₁₂N₁₂
complex exhibits the most negative ΔG (−27.33 kcal/mol in water), making it the
thermodynamically most favorable complex. The C₂₄ complex shows a positive ΔG
in gas phase (+9.12 kcal/mol), becoming weakly favorable only in aqueous medium
(+3.43 kcal/mol), indicating crucial solvation stabilization. HOMO-LUMO gaps
narrow upon complexation, particularly for Allicin/C₂₄ (2.39 eV) and Allicin/Al₁₂N₁₂
(4.41 eV), correlating with enhanced electronic reactivity and biological
target affinity [1].
Table 1. DFT thermodynamic and electronic parameters (water phase) and MD
surrogate SASA equilibrium values.
|
Complex
|
Ead
(kcal/mol)
|
ΔH (kcal/mol)
|
ΔG (kcal/mol)
|
Eg (eV)
|
SASA eq.
(nm²)
|
|
Free Allicin
|
—
|
—
|
—
|
5.78
|
13.26
|
|
Allicin/C₂₄
|
-10.54
|
-10.61
|
+3.43
|
2.39
|
11.38
|
|
Allicin/B₁₂N₁₂
|
-33.28
|
-33.13
|
-20.13
|
5.73
|
7.86
|
|
Allicin/Al₁₂N₁₂
|
-40.28
|
-40.02
|
-27.33
|
4.41
|
6.96
|
Source:
DFT data from Mozafari et al. [1], Table 1; SASA from Digital Twin MD Surrogate
(this work). Eg = HOMO-LUMO energy gap.
4.2 Layer 1 —
Degradation Kinetics and Nanocage Protection Factors
The calibrated ODE engine (Ea = 17.75 kcal/mol) yields
the kinetic parameters summarized in Table 2 at 37 °C, pH 7.4. Free allicin
degrades with k = 2.25 × 10⁻⁶ s⁻¹ and t½ = 3.6 days — consistent with
experimental values of 3.5–4 days [28]. The Allicin/C₂₄ complex provides modest stabilization (NPF
= 7.01×, t½ = 25 days) due to its shallow ΔG (−3.43 kcal/mol), while
Allicin/B₁₂N₁₂ and Allicin/Al₁₂N₁₂ (ΔG = −20.13 and −27.33 kcal/mol,
respectively) achieve NPF values of 92,166× and 5,498,905×, effectively rendering
these complexes indefinitely stable. This represents a qualitative shift from
clinically problematic lability to pharmaceutical-grade stability.
Table 2. Digital Twin kinetic parameters and Nanocage Protection Factors at T =
37 °C, pH 7.4.
|
Species
|
k (s⁻¹)
|
t½ (days)
|
Nanocage Protection Factor (NPF)
|
|
Free
Allicin
|
2.25 × 10⁻⁶
|
3.6
|
1.00×
(reference)
|
|
Allicin/C₂₄
|
3.21 × 10⁻⁷
|
25.0
|
7.01×
|
|
Allicin/B₁₂N₁₂
|
2.44 × 10⁻¹¹
|
>9,999
|
92,166×
|
|
Allicin/Al₁₂N₁₂
|
4.10 × 10⁻¹³
|
>9,999
|
5,498,905×
|
NPF
= Nanocage Protection Factor (Equation 3). Values >9,999 days indicate
effective indefinite stability.
4.3 Layer 2 — MD
Surrogate Structural Observables
The GP surrogate predictions at 200 ns equilibrium are
presented in Table 3. SASA decreases progressively from 13.26 nm² (free
allicin) to 6.96 nm² (Allicin/Al₁₂N₁₂), directly reflecting increasing solvent
exclusion upon encapsulation. B-factors decrease from 30.0 Ų to 0.676 Ų — a
44-fold reduction indicating markedly tighter binding at the interface. Rg
decreases from 5.52 to 5.38 Å, consistent with progressive structural
compaction. RMSD values are all below 0.5 Å, indicating structural rigidity of
the complexes; the Al₁₂N₁₂ complex exhibits the minimum (0.485 Å), consistent
with its highest adsorption energy.
Table 3. Equilibrium structural properties from the Gaussian
Process MD surrogate (T = 37 °C, 200 ns).
|
Species
|
RMSD eq. (Å)
|
Rg eq. (Å)
|
SASA eq. (nm²)
|
B-factor (Ų)
|
|
Free
Allicin
|
0.490
|
5.523
|
13.259
|
30.000
|
|
Allicin/C₂₄
|
0.491
|
5.486
|
11.381
|
2.572
|
|
Allicin/B₁₂N₁₂
|
0.487
|
5.396
|
7.860
|
0.804
|
|
Allicin/Al₁₂N₁₂
|
0.485
|
5.375
|
6.956
|
0.676
|
Values
represent GP surrogate predictions at t = 200 ns; ±1σ uncertainty bands shown
in figure 1B.
4.4 Layer 3a —
Stability Validation
Table 4 presents half-life validation across six temperature/pH
conditions. The Digital Twin achieves R² = 0.9997 and MAPE = 10.3%,
demonstrating excellent quantitative agreement. The largest error occurs at 4
°C (−14.5%), attributable to Arrhenius extrapolation limitations at
cold-storage conditions. At physiological (37 °C) and ambient (23 °C)
temperatures, agreement is within 12.8% and 0.0%, respectively, validating the
calibrated model.
Despite the high correlation coefficient (R2
= 0.9997) achieved with a relatively small experimental dataset (N=6), the
model’s predictive power is fundamentally grounded in physical laws rather than
purely statistical fitting. By utilizing a parsimonious approach—adjusting only
a single physical parameter (the activation energy, E_a) within a rigid
thermodynamic framework (Arrhenius and Eyring-Polanyi equations) —the risk of
overfitting is substantially mitigated. The convergence of the Digital Twin
toward an E_a of 17.75 kcal/mol aligns with the expected chemical behavior of
thiosulfinates in aqueous media, suggesting that the framework captures the
essential physics of the degradation process. Furthermore, the model’s
reliability is cross-validated by independent structural data, such as RMSD
stability and vibrational frequency accuracy, which were not part of the Nelder-Mead
optimization objective function.
Nevertheless, several limitations must be
acknowledged. First, the experimental validation dataset for half-life (N = 6
points) is small, and the near-unity R² should be interpreted with caution:
with a single free parameter and six data points, high correlation is a
necessary but not sufficient indicator of model generalizability. Independent
validation against additional experimental datasets—particularly from studies
not used in calibration—is required to confirm predictive power across broader
pH and temperature ranges. Second, the GP MD surrogate was trained exclusively
on analytically generated data, not on real GROMACS trajectories. While the
analytical expressions encode established physical principles, they cannot
capture emergent molecular dynamics phenomena such as solvent reorganization
kinetics, counterion effects, or allicin conformational transitions within the
nanocage.
Third, the NPF values for B₁₂N₁₂ and Al₁₂N₁₂ (92,166×
and 5,498,905×, respectively) are of extraordinary magnitude and must be
interpreted as theoretical upper bounds derived from the DFT ΔG values;
experimental confirmation under physiological conditions is indispensable
before any therapeutic claims can be advanced. Future work should prioritize:
(a) real GROMACS MD trajectories to retrain and validate the surrogate; (b) in
vitro stability assays of the nanocomplexes; and (c) extension of the
validation dataset with additional experimental conditions.
Table
4. Half-life
validation: Digital Twin predictions vs. experimental literature (free allicin
in water).
|
T (°C)
|
pH
|
t½ exp. (days)
|
t½ DT pred. (days)
|
Error (%)
|
Reference
|
|
4
|
7.0
|
148.0
|
126.5
|
-14.5
|
Miron et al.
[27]
|
|
23
|
7.0
|
16.0
|
16.0
|
0.0
|
Miron et al. [27]
|
|
37
|
7.4
|
3.5
|
3.95
|
+12.8
|
Lawson &
Wang [28]
|
|
50
|
7.0
|
1.1
|
1.29
|
+17.0
|
Lawson & Wang [28]
|
|
23
|
5.0
|
9.5
|
8.78
|
-7.5
|
Block [7]
|
|
23
|
9.0
|
8.0
|
8.78
|
+9.8
|
Block [7]
|
Overall:
R² = 0.9997, RMSE = 8.79 days, MAPE = 10.3%. Calibrated Ea = 17.75 kcal/mol.
4.5 Layer 3b — IR
Spectroscopy Validation
Table 5 confirms excellent DFT prediction accuracy.
The S=O stretching mode is predicted at 1065.53 cm⁻¹ vs. experimental 1070 cm⁻¹
(−0.42%), and S-S at 470.02 vs. 470 cm⁻¹ (0.00%). New interface bonds from
nanocage interaction — O-B (917.77 vs. 915 cm⁻¹, +0.30%) and O-Al (586.82 vs.
580 cm⁻¹, +1.18%) — fall within 1.2%, confirming the physical accuracy of the
DFT description of interfacial bonding [1,7].
Table 5. IR spectroscopy validation: DFT-predicted vs. experimental vibrational
frequencies.
|
Bond / Mode
|
ν exp. (cm⁻¹)
|
ν DFT (cm⁻¹)
|
Δν (cm⁻¹)
|
Reference
|
|
S=O stretch
(allicin)
|
1070
|
1065.53
|
-4.47
|
Block [7]
|
|
S-S stretch
(allicin)
|
470
|
470.02
|
+0.02
|
Block [7]
|
|
O-B stretch
(B₁₂N₁₂)
|
915
|
917.77
|
+2.77
|
Mozafari et al.
[1]
|
|
O-Al
stretch (Al₁₂N₁₂)
|
580
|
586.82
|
+6.82
|
Mozafari et al. [1]
|
Maximum
error: 1.18% (O-Al stretch). All modes within acceptable DFT accuracy threshold
of < 2%.
4.6 Layer 3c —
Molecular Docking Validation
Table 6 presents docking results across all four
therapeutic targets. Allicin/Al₁₂N₁₂ consistently achieves the strongest
binding affinity, reaching EDc = −7.21 kcal/mol for both HER2 and S. aureus
targets — nearly doubling the affinity of free allicin (−3.78 and −4.15
kcal/mol, respectively). For COVID-19 Mpro, improvement from −3.79 to −6.74
kcal/mol is therapeutically significant. Allicin/B₁₂N₁₂ consistently shows the
weakest affinities, consistent with its highest HOMO-LUMO gap (5.73 eV) and
intermediate thermodynamic properties [1].
Table
6. Molecular docking
binding affinities for allicin and nanocomplexes against four therapeutic
targets.
|
Target
|
Ligand
|
EDc (kcal/mol)
|
Ki (µM)
|
Key Interaction
|
|
HER2
|
Free Allicin
|
-3.78
|
1.70
|
H-bond ASP863
|
|
HER2
|
Allicin/C₂₄
|
-5.42
|
578.25
|
H-bond CYS805
|
|
HER2
|
Allicin/B₁₂N₁₂
|
-2.49
|
80.65
|
H-bond LYS753
|
|
HER2
|
Allicin/Al₁₂N₁₂
|
-7.21
|
27.98
|
H-bond LYS753; hydrophobic LEU852
|
|
TNF-α
|
Free Allicin
|
-3.74
|
1.81
|
H-bond ILE136
|
|
TNF-α
|
Allicin/C₂₄
|
-3.34
|
19.15
|
Hydrophobic ILE136
|
|
TNF-α
|
Allicin/B₁₂N₁₂
|
-1.03
|
944.49
|
H-bond ILE136,
LEU26
|
|
TNF-α
|
Allicin/Al₁₂N₁₂
|
-4.48
|
1.54
|
H-bond ILE136; electrostatic GLN25
|
|
COVID-19 Mpro
|
Free Allicin
|
-3.79
|
1.68
|
H-bond TYR54
|
|
COVID-19 Mpro
|
Allicin/C₂₄
|
-5.59
|
435.04
|
H-bond GLU166
|
|
COVID-19 Mpro
|
Allicin/B₁₂N₁₂
|
-2.79
|
48.46
|
Non-conv. H-bond
GLY143
|
|
COVID-19 Mpro
|
Allicin/Al₁₂N₁₂
|
-6.74
|
61.62
|
H-bond HIS41, GLY143, CYS145
|
|
S. aureus
|
Free Allicin
|
-4.15
|
907.75
|
H-bond THR635,
GLY620
|
|
S. aureus
|
Allicin/C₂₄
|
-4.83
|
1.55
|
Electrostatic GLU623
|
|
S. aureus
|
Allicin/B₁₂N₁₂
|
-1.86
|
235.96
|
Electrostatic
THR619
|
|
S. aureus
|
Allicin/Al₁₂N₁₂
|
-7.21
|
28.00
|
Hydrophobic TYR636
|
PDB IDs: HER2
(3RCD), TNF-α (2AZ5), COVID-19 Mpro (6LU7), S. aureus (3VSL). Source: Mozafari
et al. [1].
4.7 Figures —
Digital Twin Integrated Visualization
The five figure panels present all Digital Twin
outputs in clear, accessible format for detailed visualization. Each panel is
self-contained with a complete caption.
Figure 1A. ODE kinetic layer results at T = 37 °C, pH 7.4. (a)
Temporal degradation curves for all species: free allicin (t½ = 3.6 days),
Allicin/C₂₄ (t½ = 25 days), Allicin/B₁₂N₁₂ and Allicin/Al₁₂N₁₂ (t½ > 9,999
days). Vertical dotted lines mark half-life points; dashed orange curve =
cumulative degradation products. (b) Nanocage Protection Factors (NPF) on log₁₀
scale with corresponding half-life annotations. Horizontal dashed line = free
allicin reference (NPF = 1). Al₁₂N₁₂ achieves NPF = 5.5 × 10⁶, representing a
5.5 million-fold stabilization.
Figure 1B. MD surrogate structural observables (Gaussian Process
emulation, T = 37 °C, 200 ns simulation). (a) RMSD trajectories: all complexes
equilibrate below 0.5 Å; Al₁₂N₁₂ reaches the minimum (0.485 Å), reflecting
structural rigidity of strong encapsulation. (b) Radius of gyration (Rg):
progressive compaction from free allicin (5.52 Å) to Al₁₂N₁₂ complex (5.38 Å).
Shaded bands represent ±1σ Gaussian Process prediction uncertainty.
Figure 1C. MD surrogate solvent exposure and thermal flexibility.
(a) SASA trajectories: free allicin equilibrates at 13.26 nm² while
Allicin/Al₁₂N₁₂ reaches 6.96 nm² — a 47% reduction reflecting deep encapsulation.
(b) Equilibrium B-factor (solid bars) and SASA (transparent bars) by species:
the 44-fold B-factor reduction from free allicin (30.0 Ų) to Al₁₂N₁₂ complex
(0.676 Ų) indicates markedly tighter atomic fluctuation at the binding
interface.
Figure 1D. Experimental validation layer. (a) Half-life
predictions vs. experimental literature across six temperature/pH conditions:
R² = 0.9997, MAPE = 10.3% [27,28].
(b) IR vibrational frequency comparison: DFT-predicted vs. experimental
wavenumbers for S=O stretch, S-S stretch, O-B stretch, and O-Al stretch; error
labels indicate percentage deviation (maximum: +1.18% for O-Al) [1,7].
Figure 1E. Docking affinities and stability landscape. (a)
Molecular docking binding energies (EDc, kcal/mol) for all four species against
HER2, TNF-α, COVID-19 Mpro, and S. aureus — Allicin/Al₁₂N₁₂ consistently
achieves the strongest affinity (most negative EDc) across all targets [1]. (b) Free allicin
stability landscape across temperature (°C) and pH space; color scale =
predicted t½ (days, capped at 300). ★ = physiological conditions (37 °C, pH 7.4); ▲ =
standard lab storage (23 °C, pH 7.0); ■ = cold storage (4 °C, pH 7.0).
CONCLUSION
This study presents the first Digital Twin framework
for modeling aqueous degradation of a natural bioactive compound — allicin —
and its Al₁₂N₁₂, B₁₂N₁₂, and C₂₄ nanocomplexes. The three-layer architecture
successfully integrates DFT thermodynamic data [1], Gaussian Process MD surrogate emulation, and
multi-source experimental validation into a unified, adaptive computational
system.
Principal findings: (i) Allicin/Al₁₂N₁₂ achieves NPF =
5.5 × 10⁶ at physiological conditions (37 °C, pH 7.4), extending t½ from 3.6
days to beyond 9,999 days — resolving allicin's principal pharmacological
limitation if confirmed experimentally. (ii) The GP surrogate accurately
captures structural encapsulation signatures: SASA decreases from 13.26 nm²
(free) to 6.96 nm² (Al₁₂N₁₂), and B-factor from 30.0 to 0.676 Ų. (iii)
Stability prediction achieves R² = 0.9997, MAPE = 10.3%; IR frequencies within
1.18%. (iv) Allicin/Al₁₂N₁₂ ranks first in binding affinity against all four
targets (HER2, TNF-α, COVID-19 Mpro, S. aureus) [1].
The data assimilation module allows recalibration in
minutes as new experimentais datas (GROMACS trajectories, UV-vis, or stability
measurements) become available. Future work will focus on: (a) validation with
real GROMACS MD trajectories; (b) drug release kinetics modeling in simulated
gastrointestinal fluid; (c) ADMET integration; and (d) extension to DADS and
ajoene nanocomplexes.
CONFLICT
OF INTEREST
The
authors declare no conflict of interest.
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